Semiconductor device

Abstract

According to one embodiment, a semiconductor device includes a first conductivity type base layer, a second conductivity type base layer, a gate insulating film, a first conductivity type source layer, a gate electrode, and a main electrode. The gate electrode is provided inside of the gate insulating film in the trench. The main electrode is provided on the surface of the second conductivity type base layer and on a surface of the first conductivity type source layer. The main electrode is provided at a position deeper than the gate electrode and the second conductivity type base layer in the trench. The main electrode is electrically connected to the second conductivity type base layer and the first conductivity type source layer.

What is claimed is: 
     
         1 . A semiconductor device comprising:
 a first conductivity type base layer;   a second conductivity type base layer provided on the first conductivity type base layer;   a gate insulating film provided on a side wall of each of a plurality of trenches which reach the first conductivity type base layer from a surface of the second conductivity type base layer;   a first conductivity type source layer selectively provided on the surface of the second conductivity type base layer adjacently to the gate insulating film;   a gate electrode provided inside of the gate insulating film in the trench; and   a main electrode provided on the surface of the second conductivity type base layer and on a surface of the first conductivity type source layer, provided at a position deeper than the gate electrode and the second conductivity type base layer in the trench, and electrically connected to the second conductivity type base layer and the first conductivity type source layer.   
     
     
         2 . The device according to  claim 1 , wherein
 the main electrode has:
 a surface electrode provided on the surface of the second conductivity type base layer, on the surface of the first conductivity type source layer, and on the trench; and 
 a buried electrode which extends in the depth direction in the trench from the surface electrode on the trench to a position deeper than the gate electrode. 
   
     
     
         3 . The device according to  claim 2 , wherein
 a pair of the gate electrodes are provided in the one trench; and   the buried electrode is provided between the pair of gate electrodes.   
     
     
         4 . The device according to  claim 2 , further comprising:
 a second conductivity type semiconductor layer provided between the adjacent trenches on the first conductivity type base layer and in an electrically floating state.   
     
     
         5 . The device according to  claim 4 , wherein
 the gate electrode is provided between the first conductivity type source layer and the buried electrode; and   the buried electrode is provided between the gate electrode and the second conductivity type semiconductor layer.   
     
     
         6 . The device according to  claim 4 , wherein
 the second conductivity type semiconductor layer is located at a position deeper than the second conductivity type base layer.   
     
     
         7 . The device according to  claim 4 , wherein
 the trench separates the second conductivity type base layer and the second conductivity type semiconductor layer from each other.   
     
     
         8 . The device according to  claim 4 , further comprising:
 a collector electrode; and   a second conductivity type collector layer provided between the collector electrode and the first conductivity type base layer, wherein   the second conductivity type base layer and the second conductivity type semiconductor layer have second conductivity type impurity concentration lower than that of the collector layer.   
     
     
         9 . The device according to  claim 4 , wherein
 the second conductivity type semiconductor layer does not have a first conductivity type region provided.   
     
     
         10 . The device according to  claim 1 , wherein
 the main electrode has:
 a surface electrode provided on the surface of the second conductivity type base layer and on the surface of the first conductivity type source layer; and 
 a buried electrode provided below the gate electrode in the trench through an insulating film. 
   
     
     
         11 . The device according to  claim 10 , further comprising:
 a second conductivity type semiconductor layer provided between the adjacent trenches on the first conductivity type base layer and in an electrically floating state.   
     
     
         12 . The device according to  claim 11 , wherein
 the second conductivity type semiconductor layer is located at a position deeper than the second conductivity type base layer.   
     
     
         13 . The device according to  claim 11 , wherein
 the trench separates the second conductivity type base layer and the second conductivity type semiconductor layer from each other.   
     
     
         14 . The device according to  claim 11 , further comprising:
 a collector electrode; and   a second conductivity type collector layer provided between the collector electrode and the first conductivity type base layer, wherein   the second conductivity type base layer and the second conductivity type semiconductor layer have second conductivity type impurity concentration lower than that of the collector layer.   
     
     
         15 . The device according to  claim 11 , wherein
 the second conductivity type semiconductor layer does not have a first conductivity type region provided.   
     
     
         16 . The device according to  claim 10 , further comprising:
 a second insulating film provided between the buried electrode and the first conductivity type base layer.   
     
     
         17 . The device according to  claim 1 , further comprising:
 a collector electrode; and   a second conductivity type collector layer provided between the collector electrode and the first conductivity type base layer.